I don't have the best track of Kristo, but my take so far is that Kristo is a little more of a high maintainance player and probably competes for quite alot "fewer" spots than Fast. Kristo has obviously grown into the role of being a goto scorer/franchise player in College. He has picked up alot of abilities that are very valueble and rare in the process. In the NHL, he is going to have to find away to contribute while being say 5th - 7th on the deptchart of forwards. That is a transition in itself. Many players have made that transiton, guys like Versteeg, Jarret Stoll and several others. But if often takes some time and he got some work left to get there. Fast is more in the Hagelin mold who just can hit the ice and go.
Fast hasn't dominated on the scoreboard atleast so far, but I think -- to be perfectly honest -- that is more about Gernander being clueless than Fast not getting it done. As it is now he is playing out of position on a line with a, not necessary in a negative way, puck-hog in Kristo and a dominating center in Lindberg.
Fast could definitely alone carry a line at this level, and if Gernander split him up and put him at RW with like Duclair and St Croix, we would have two dominating lines instead of one. But it is what it is.
Also re the roster, I think we are good up front but have a weak blueline.